Carburetor



May 19, 1936. F. J. BURRows ET Al. `2,041,524

MEM/Zz/RMWS/ 5)/ m Arron/VE YS May 19, 1935 F. J. BURRows ET Al. 2,041,524

CARBURETOR FiLed June 14, 1932 2 Sheets-Sheet 2 21312517 JURRUv/.Sz' /x//LL/AM HEURE@ W5.'

5) www f W ATTORNEYS Patented May 19, 1936A UNITED STATES CARBURETOR Fred J. Burrows, Ticonderoga, and William H. Burrows, Crown Point, N. Y.

Application June 14, 1932, Serial No. 617,126

12 Claims.

Our invention more particularly relates to a carburetor for internal combustion engines and especially to a. device in which the liquid hydrocarbon which is used as a fuel is preheated to a sufficiently high temperature to Vaporize the same before the main portion of the air forming part of the fuel charge is intermixed therewith, thereby maintaining the main supply of air at as lo-w a temperature as possible.

A fuel charge for an internal combustion engine is ordinarily formed by the intermixture of air and a liquid hydrocarbon, the quantity of air being determined by the quantity of oxygen necessary to produce a mixture having the desired l5 combustible qualities and the quantity of oxygen thus supplied being generally so proportioned as to cause combustion of the oxygen and liquid hydrocarbon.

lt has hitherto been proposed to preheat the air. Such preheating, however, causes it to expand so that there is much less oxygen by weight in a given volume than when the air is of a. lower temperature.

We have found that, with the usual carburetor,

y the most eiicient mixture of air and gas is produced when the engine is idling. As the speed of the engine increases, however, the amount of gas increases more rap-idly than does the amount of air with the result that the mixture is less efcient.

One of the objects of our invention is the provision of means for causing the amount of air to increase proportionally with the amount of gas at higher speeds.

Other objects of our invention will appear in the specification and will be particularly pointed out in the claims.

Our invention will best be understood by reference to the accompanying drawings in which we have illustrated a preferred embodiment thereof and in which- Fig. l is a side elevational view, partially in section, of our device, the auxiliary air chamber being omitted;

Fig. 2 is a sectional elevation, taken about on the line 2 2 of Fig. l;

Fig. 3 is a fragmentary plan view of a portion of the device embodying our invention;

Fig. 4 is an enlarged sectional view of the member to which the fuel and the air which aspirates the fuel is supplied;

Fig. 5 is a detail sectional View; Fig. 6 is a sectional plan taken on the line 6--6 0f Fig. 1;

Cil

Fig. 7 is a section taken on the line I--l of Fig. 2; and

Fig. 8 is a fragmentary perspective view of our device illustrated in mounted position with respect to the intake and exhaust manifolds of an internal combustion engine.

Like reference characters indicate like parts throughout the drawings.

Referring now to the drawings I0 indicates generally the inlet pipe for the major portion of 10 the air supply for the fuel charge provided with the usual butterily valve II and having an enlarged chamber at I2 the upper walls of which are inclined as at I3 to form a seat for the valve I4 controlling the amount of air supplied through 15 the pipe I. The valve I is mounted on a valve stem l5 guided by a cross bar I5I formed in the main air supply pipe I3, the lower end of said stem being received in a recess I6 formed in a screw plug II which is received in a tapped open- 20 ing I8 in a plate I9. This plate is preferably screw threaded and engages screw threads formed on the interior of the lower portion of a cylinder 20. The screw plug Il is adjustably secured in position by a lock nut 2|. 25

A disc 22 is adjustably secured on a screw threaded portion 23 of the valve stem I5 and is secured in the desired position by a lock nut 24. The disc 22 forms a fairly close t within the cylinder 20 thereby forming a dashpot and pre- 30 venting abrupt movements of the valve I4. An adjustable valve 25 is provided to regulate the escape of air from the dashpot, whereby the rapidity of movement of the valve I4 may be controlled to suit the necessary conditions. 35

A coil spring 26 is interposed between the disc 22 and the plate I9 and normally lifts the disc 22 against a shoulder 27 formed .in the pipe I0, and the disc 22 is so adjusted on the stem that when it is seated against the shoulder 2l, the 40 valve I4 is slightly open.

The pipe I 0 is preferably enlarged as at a point 28 for a purpose which will hereinafter be pointed out, and is provided, beyond this point, where the fuel is mixed with the main air supply, with the usual throttle valve 29. The pipe I 0, from this point conducts the thoroughly mixed gases to the usual intake manifold 20, illustrated in Fig. 8. Referring now particularly to Figs. 2 5 and 4, 3U is a oat chamber which is provided with the usual float 3| and having a needle valve 32 controlling the supply of yliquid fuel to the chamber through the liquid fuel inlet 33. The p float chamber is preferably supported by a brack-l 55 Ulr et 34 which may be clamped or otherwise secured as at 35 to the air inlet pipe IU.

Liquid fuel is supplied to the carburetor by a pipe 36 the supply end of which is received in an offset recess 31 formed in the wall of the iioat chamber, as best shown in Fig. '1, so that it does not interfere with the operation of the float. The other end of the pipe 36 is secured as by a coupling 36| to a block 39 and communicates with an opening 38 therein which is supported on the upper wall 40 of a heating chamber 4|. The block is provided with an opening 42 the wall around the upper portion of which is screw threaded, the lower end of the opening being cone shaped as at 43. An air inlet nozzle 44 is provided with screw threads engaging those surrounding the opening 42. A plain cylindrical portion of the air nozzle 44 is spaced from a plain cylindrical portion of the opening 42 to form an annular recess 45 communicating with the passage 38 in the block 39. The lower end of the air inlet nozzle 44 is tapered and is slightly spaced from the walls of the opening 42 to form an annular opening through which the liquid fuel may fiow. The supply of liquid fuel to the recess 42 may be adjustably controlled by a needle valve 46, the shaft of which extends through the substantially horizontal portion of the pipe 36 and is provided with an adjusting wheel 352.

The air nozzle 44 and the orifice 43 surrounding the same communicate with a tubular element 41 passingdownwardly through the heating chamber 4| and opening into the main air supply pipe l0, the lower end of the tubular element preferably being beveled as at 48, the open beveled end of the pipe facing away from the incoming air, so that the main body of air creates an aspirating effect on the tubular element 41. By enlarging the air inlet pipe at 28 around the lower end of the pipe 41, the latter does not choke the fiow of air. The passage in the lower end of the tubular element 41 is preferably constricted as at 49 to produce the desired drop in pressure between the main air supply pipe |6 and the upper portion of the tubular element 4l.

A cone shaped baille 50 is located beneath the orifice of the air nozzle 44 and the liquid fuel orifice 43 and serves to break up the air and gas as it enters the tubular element and deiiects the same against the walls thereof. The heating chamber 4| is preferably secured to the exhaust manifold 5|, the wall of the manifold to which the heating chamber is secured preferably being provided with an opening 52 which communicates with the heating chamber 4|, the portion of the heating chamber adjacent to the manifold being open. The exhaust manifold is provided With a baffle 54 mounted on the wall opposite to the opening in the manifold and it serves to direct gases into the heating chamber 4|.

Auxiliary or additional air is preferably supplied to the tubular element 41 by a pipe 55 cornmunicating therewith. The cross sectional area within the pipe 55 which supplies additional or auxiliary air to the tubular element 41 is at least as large and preferably larger than that in the passage in the tubular element 41 with which it communicates. The other end of the pipe 55 communicates with a cylinder 56 provided with means for controlling the admission of air thereto. A poppet valve 51 normally engages a Valve seat 58 formed in a head 59 which is preferably screw threaded and received in the screw threaded end of the cylinder 56. The Valve seat 58 and the engaging surface of the valve preferably form an acute angle with the axis of the valve so that a comparatively large movement of the valve produces only slight variations in the size of the opening between the valve and its seat and correspondingly small variations in the amount of auxiliary air supplied to the tubular element. The valve 51 is provided with a stem 60 formed with a recess 6| in which is received a stem 62. The lower portion of the stem 62 is provided with screw threads whereby it may be adjustably mounted in a plate 64 closing the lower end of the cylinder 56. A lock nut 63 is provided to secure the stem 62 in any desired position. Of course, the construction of the valve adjusting means and its application to the plate 64 may be essentially the same as the plate I9 and the screw threaded portion 23 illustrated in Fig. 2. A compression spring 65 is interposed between the valve head 51 and the plate G4. The

than the corresponding air supply with the result l that the mixture is less eflicient at higher speed than when the engine is idling. In accordance with our invention, as the speed of the engine increases the supply of air increases in proportion, or substantially so, to the increase in the supply of liquid fuel. As the speed of the engine increases the vacuum in the main air inlet ||l becomes higher and this causes the auxiliary valve 51 to open and thereby admit auxiliary air to the mixture of vaporized fuel and air which is flowing through the pipe 41.

At the same time the opening of the valve 51 reduces the Vacuum in the pipe 41 as compared with what it would be without the valve and while the amount of gasolene supplied is increased, the increase is less than it would be without the Valve. It is important that the valve 51 should be provided with a seating -face having a steep pitch since comparatively large movements of the valve produce only comparatively small variations in the valve opening. By forming the valve in this manner the increase in the curves defining the increases in air and fuel with increases in engine speed are kept substantially r parallel.

The auxiliary air supply admitted past the valve 51 is mixed with the mixture of vaporized fuel and air from the nozzle 41, and the complete mixture enters the main air inlet in the form of a gas.

An air supply pipe 66 is connected to the air inlet nozzle 44 and preferably lies adjacent to the exhaust manifold 5|, as illustrated n Fig. l, so that the air supplied to the nozzle 44 is preheated.

The operation o'f the device embodying our invention will readily be understood from the foregoing description and is as follows.

The main air supply is drawn into the pipe l0 by a vacuum or partial vacuum created in the air supply pipe in the usual manner. As a result of a restriction being disposed in the lower portion of the tubular element 41 the degree of vacuum produced in said tubular element may be confined within any desired limits; preferably, this vacuum Cab will'be sufficient to 'cause a proper quantity of air to flow through the nozzle 44. The incoming air through nozzle 44 aspirates liquid fuel from the float chamber through the pipe 36, said fuel owing past the needle valve 46, being regulated thereby, and then flowing through the annular orice 43 surrounding the lower end of the air inlet nozzle 44. The nozzle 44 is adjusted so close to its seat that when the throttle is open liquid fuel flows through the annular orifice surrounding the air jet. The thin sheet of liquid fuel thus admitted is constantly broken up by the expansion of air taken in through the pipe 66 and passing downwardly through the nozzle 44. This expansion of air, assisted by the baille 5D, causes the liquid fuel and the air combined therewith to ilow in contact' with the tubular member 41 which heats the fuel and air as it flows downwardly within the tubey sufficiently to vaporize the same. As the throttle is opened, this vaporizing effect is increased, the result of which is opposite to that secured with the ordinary carburetor.

The fuel which is so vaporized and which is already mixed with the air entering through the nozzle 44, is then mixed with the auxiliary air admitted past the valve 5l with the result that the liquid fuel, together with the air admitted through the above described openings, enters the main air inlet pipe ID as a vapor. The result attained by this device wherein the liquid fuel is vaporized and to some extent mixed with air and then combined with the main air supply, produces a uniform mixture of gas which results in an even and more efficient burning in the cylinders of an internal combustion engine, an added. feature being a substantial elimination of knocking and hammering in the cylinders and at the same time giving a maximum power output with a minimum consumption of fuel. Furthermore, a decided advantage in our device is the 'fact that an engine using our device operates at a lower temperature than when using other carburetors with which we are familiar.

We have found that an engine equipped with our invention operates satisfactorily when kerosene has been added to gasoline in the proportion of one part kerosene to three parts gasoline and the resultant operation and power produced therewith are comparable to that secured when high test gasoline is used with the ordinary carburetor and, furthermore, that even in cold weather no trouble is experienced either in the running or starting of the motor. A further result is achieved which is advantageous in that an increase in flame propagation is secured.

It will be understood that only a relatively small amount of warm air is introduced through the air inlet nozzle 44, the proportion of air to liquid fuel being increased through the auxiliary air supply pipe 55. This auxiliary air supply pipe 55 is controlled by the valve 51 opening or closing by means of a vacuum produced in the air inlet pipe I and in the tubular element 4l' and the action of the spring 65, respectively. By means of the proper regulation of the air control means, a proper mixture of air and liquid fuel is produced and is thus introduced to the inlet pipe I0 in such proportions as to form with the air in the inlet pipe a mixture which produces complete combustion.

It will also be understood that the valve I4 associated with the main air supply pipe I0 regulates the main supply of air which is used to produce a combustible gas for introduction into the cylinders of an engine. The operation of this valve depends upon the vacuum producedl in the pipe l 0 and hence this main supply of air is also automatically regulated by the variations in the vacuum produced in the pipe l0. Therefore, it will be seen that the air supply for aspirating the liquid fuel, the auxiliary air supply and the main air supply are regulated by and depend upon the vacuum produced in the pipe I0. Y

While we have described our invention in its preferred embodiment, it is to be understood that the words which we have used are words of description rather than of limitation and that changes within the purview of the appended claims may be made without departing from the true scope and spirit of our invention in its broader aspects.

What we claim is:

1. In a down draft carburetor, means forming a passage for the major portion of the air for the fuel charge, a source of liquid fuel, a tubular element extending downwardly and opening into said passage and communicating at the top with the atmosphere and with the liquid fuel source whereby fuel is aspirated from said source and flows downwardly in said element, and means comprising a normally closed poppet valve operable in response to a reduction in pressure in said air passage for admitting additional air to said tubular element, the seat for said Valve forming an acute angle with the axis thereof whereby comparatively large movements of said valve produce comparatively small variations in the amount of additional air supplied to said tubular element.

2. In a down draft carburetor, means forming a passage for the major portion of the air for the fuel charge, a source of liquid fuel, a tubular element extending downwardly and opening into said passage and communicating at the top with the atmosphere and with the liquid fuel source whereby fuel is aspirated from said source and iiows downwardly in said element, means for deflecting the mixture of air and fuel into engagement with the walls of said tubular element, a heating element surrounding said tubular element, and means responsive to a reduction in pressure in said air passage for admitting additional air to said tubular element and reducing the drop in pressure therein.

3. In a down draft carburetor, means forming a duct for the major portion of the air for the fuel charge, means forming an orifice through which a hydrocarbon forming part of the fuel charge is aspirated, a tubular element extending downwardly and opening into said duct and communicating at the upper portion with the atmosphere and with said orifice whereby fuel is aspirated from said orifice and flows downwardly into said element, means for deflecting the fuel against the walls of said element, means for heating said element, and means for introducing auxiliary air into said element after the mixture has been heated.

4. In a carburetor, means forming a passage for the major portion of the air for the fuel charge, a liquid fuel supply, a tubular element opening into said passage and communicating with the atmosphere and with the liquid fuel supply whereby fuel is aspirated from said supply and flows into said element, means for deflecting the mixture of air and fuel into engagement with the walls of said tubular element, means forming a heating chamber surrounding said element and means responsive to a reduction in pressure in said air passage for introducing additional air to the mixture Within said tubular element after it has been heated by said chamber.

5. A carburetor comprising a duct communieating with the atmosphere and through which the major portion of the air for the fuel charge is drawn, a throttle valve in said duct, a second and smaller duct communicating with the atmosphere and with said rst mentioned duct at a point intermediate the throttle and atmosphere and through which air for aspirating a liquid fuel is drawn, a liquid fuel source from which liquid fuel is aspirated into said second duct, and a third duct communicating at all times with said second duct, at a point intermediate the fuel entrance thereto and the first duct, and with the atmosphere through a Valve opened by suction in said third duct.

6. A carburetor comprising a first duct communicating with the atmosphere and of a size adapted to pass substantially all the air necessary to form the fuel charge for an internal combustion engine, a throttle valve in said duct, a fuel aspirating duct communicating with the atmosphere and with the first duct at a point therein intermediate the throttle and atmosphere and through which air for aspirating a liquid fuel is drawn, a liquid fuel source communicating with said aspirating duct, means relatively remote from said first duct for heating said aspirating duct and the fuel passing therethrough, whereby the liquid fuel is heated without substantially heating the air passing through the first duct, and a third duct communicating with said aspirating duct, at a point intermediate the fuel entrance thereto and the first duct, and with the atmosphere through a Valve opened by suction in said third duct; whereby, when said throttle valve is opened, additional air is admitted directly to the aspirating duct and tends to reduce the volume of liquid fuel drawn therethrough.

7. A down draft carburetor comprising a main air duct, a oat chamber for liquid fuel, a fuel aspirating duct communicating at its upper end With the atmosphere, at its lower end with the main air duct, and at an intermediate point with said oat chamber, a jacket relatively remote from the main air duct surrounding said aspirating duct between its point of communication with the float chamber and the main air duct and adapted to permit the passage of hot exhaust gases therethroughwhereoy to heat the aspirating duct without substantially heating the main air duct, and a third duct communicating with said aspirating duct, at a point intermediate the fuel entrance thereto and its junction with the main air duct, and with` the atmosphere` through a valve opened by suction in said third duct whereby air may be admitted directly to the aspirating duct.

8. In a down draft carburetor, a main air duct through which the major portion of the air forming the fuel charge is drawn, a second vertically extending fuel aspirating duct communicating at its lower end with said main duct, an air inlet nozzle opening into the upper end of said second duct, means for admitting a liquid fuel to said duct around said nozzle, means responsive to'a drop in pressure in said second duct for admitting additional air thereto at a point intermediate said nozzle and said main duct, and means relatively remote from the main air duct for heating said second duct, whereby to heat and vaporize the liquid fuel before intermixing it with the main air supply while maintaining said main air supply substantially at the density of the circum ambient air.

9. In a carburetor, the combination with a main air duct, of a fuel aspirating duct communicating with said main air duct and the atmosphere, means forming a passage through which liquid fuel is aspirated and delivered to said aspirating duct at a point therein intermediate the main air duct and the atmosphere, and means responsive to a reduction in pressure in that zone of the aspirating duct between the main duct and the fuel delivery point for supplying additional air to said zone.

10. A down draft carburetor comprising a main air duct, a valve opened by suction in said duct for controlling the flow of air therethrough, a

throttle in said duct, a fuel aspirating duct com- "s municating with said main duct intermediate said valve and throttle, means for conducting and delivering a liquid fuel to said aspirating duct at a point therein spaced from said main duct, and means responsive to a reduction in pressure in said aspirating duct for admitting additional air thereto at a point between the main duct and the fuel delivery point.

l1. A down draft carburetor comprising a main air duct, a valve opened by suction in said duct for controlling the flow of air therethrough, a throttle in said duct, a fuel aspirating duct communicating with said main duct intermediate said valve and throttle, means for conducting and delivering a liquid fuel to said aspirating duct at a point therein spaced from said main duct, means responsive to a reduction in pressure in said aspirating duct for admitting additional air thereto at a point between the main duct and the fuel delivery point, and means relatively remote from the main air duct for heating the aspirating duct whereby to preheat the liquid fuel while maintaining the air flowing through said main duct substantially at the density of the circumambient air.

12. In a carburetor, the combination with a main air duct through which the major portion of air going to make up the fuel charge is drawn, of a second duct communicating at one end with the atmosphere and at the other end with the main air duct and through which a liquid fuel is aspirated, means for conducting liquid fuel to said second duct and delivering it therein at a point spaced from said main duct, a third duct communicating with said second duct at a point therein intermediate the main duct and said fuel delivery point, and a normally closed valve in said third duct operable by suction in said third duct to admit air thereto.

FRED J BURROWS. WILLIAM H. BURROWS. 

